1. Technical Field of the Invention
The present invention relates to rate conversion, and more particularly, to a rate conversion within radio telecommunication's equipment that does not require a common divider.
2. Description of Related Art
The expansion of cellular telephone communications technologies has provided a boon in the ability of the public to communicate using wireless services. However, the development of wireless technologies have resulted in different standards of services being available for users. Thus, the situation may arise where a single wideband receiver may be required to operate with different types of systems. There are several system types available that provide mobile communication services to users. Some major ones are the Advanced Mobile Phone Service (AMPS), which is an analog wireless communication standard; the Digital Advanced Mobile Phone Service (D-AMPS), which is a digital cellular communication standard; and the Global System for Mobile Communication (GSM), which is another digital standard.
During operations of a cellular telephone network, it is possible that a single wideband receiver may be required to operate with both a AMPS/D-AMPS base station and a GSM base station. When a wideband receiver sends information to base band units using different standards, a problem arises from the differing clock frequencies defined by each standard. In order to find commonality between the different systems, a very high common divider (if available) must be determined. For example, within an AMPS/D-AMPS base station, the first usable common frequency is 19.44 MHZ. For a GSM system, the frequency used used is 13 MHZ. The first available common divider for all of these standards is 6.318 GHz (13.times.486=19.44.times.325). This high common divider makes it very difficult to perform rate conversions with the help of known interpolating/decimation filters which do not operate at this high frequency level. Thus, some improved method for performing rate conversions between differing systems would be greatly beneficial to the wireless communications industry.